$(-3+71i)+(9)=$ Express your answer in the form $(a+bi)$.
Background Complex numbers can be added or subtracted by separately adding or subtracting their real and imaginary terms. To add or subtract complex numbers: Expand parentheses (attending to minus signs outside of parentheses if necessary) Combine all real terms (terms that do not contain $i$ ), and add or subtract them. Combine all imaginary terms (terms that contain $i$ ), and add or subtract them. Combining Like Terms $\begin{aligned} ({-3}+{71}i)+({9})&={-3}+{71}i+{9} \\\\ &={-3}+{9}+{71}i \\\\ &={6}+{71}i \end{aligned}$ Summary $({-3}+{71}i)+({9})={6}+{71}i$